The present invention relates generally to radio frequency identification (RFID) systems and devices. More particularly, the present disclosure relates to systems and devices for further confining and focusing radio frequency energy when applied with the use of RFID transponders that are moving in high speed linear motion through use of a conveyance to allow for the singulation of carton contents.
Radio frequency identification (RFID) tags are electronic devices that may be affixed to items whose presence is to be detected and/or monitored. The presence of an RFID tag, and therefore the presence of the item to which the RFID tag is affixed, may be checked and monitored by devices known as “readers” or “reader panels.” Readers typically transmit radio frequency signals to which the RFID tags respond. Each RFID tag can store a unique identification number. The RFID tags respond to reader-transmitted signals by providing their identification number and additional information stored on the RFID tag based on a reader command to enable the reader to determine an identification and characteristics of an item.
Currently, the need for the ability to scan RFID transponders in automated environments has caused the creation of a scanning tunnel or enclosure. Different manufacturers may take different approaches to scanning these transponders. Typically, an enclosure uses a combination of absorber material to attenuate radio frequency energy and a read chamber central to the enclosure that projects a read zone. Thus, the read chamber uses an absorber method that directs the main flow of energy normal to the antenna plane, creating the read zone. However, although this does create a field or read zone, it does not allow for tuning of the read zone. Refinement (or tuning) of the leading edge signal of the read zone is critical to the success of reducing the overall gap or spacing required between cartons. Further, some degree of tuning can be done by means of power modulation to the antenna contained within the read chamber. However, this is only marginally effective as a function of the power decreases so does the effectiveness of the reader to energize the transponders.
The present invention discloses a read chamber device that provides for tuning (or reducing) the read zone via a movable metal plate that is positioned at variable distances to partially or fully cover the read zone. The metal plate is moved into the read zone to obstruct a percentage of radio frequency energy from escaping the read zone, and thus narrowing the total read field and refining the leading edge signal of the read zone. Further, the disclosed read chamber device does not require power modulation for tuning and allows the use of high reader power without causing an extension of the RF field beyond a defined area. Thus, the read chamber device, in combination with the use of metallic and absorption materials allows for the singulation of carton contents.